Aug 14

Recreating a vmdk descriptor file with vmkfstools

A VMware virtual machine disk is made up of two files: the .vmdk file and the -flat.vmdk file. The .vmdk file is the descriptor file and the -flat.vmdk file contains the data. If you have the -flat.vmdk file you can recreate the descriptor file using vmkfstools. This VMware KB: Recreating a missing virtual machine disk descriptor file (1002511) walks through the process.

This just saved my butt (again, but it has been awhile) so putting it here for future reference.

Jul 17

Jumbo Frames – Make sure it is setup end-to-end.

Working with a customer the other day to migrate his direct connect SimpliVity deployment to a 10 GbE switch topology to facilitate adding a couple of compute nodes to expand the CPU and memory resources available to the cluster. He went through the migration but could not get things to work correctly. The issue ended up being the MTU configuration on the physical switch.

Mis-configuration of the physical switch is probably the most common issue I come across when configuring virtual networking to use Jumbo Frames. The configuration varies from switch to switch – vendor to vendor. On some switches the configuration is done globally, on other switches it is configured on individual ports, and on some switches it must be enabled globally and configured per port.

Jumbo Frames must be configured correctly end-to-end. This means on the vSwitch, vmkernel interfaces, physical switches, endpoint – everything must be configured to support the larger frames end-to-end. Using larger frames will provide more efficient processing of network traffic (in many cases) but it does require a bit more complexity. If any part of the path is mis-configured, network frames larger than 1500 may not pass. If they do pass they will be fragmented, which defeats the purpose of using Jumbo Frames.
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Jul 03

DIY Garage Workbench

This post is not about virtualization, my home lab, or technology. Going a little low tech here to share a DIY project I did over the weekend, a mobile garage workbench using some free plans I found over at

The workbench turned out really nice, is very sturdy, and easy to move around. I haven’t decided to paint it or not. Will probably just leave it raw and put a coat of clear poly on the top and shelf to seal them. The lumber and screws required to build the workbench came in at $63 from Lowe’s and the casters were $24, so all total $87 (plus the cost of the Kreg R3 Jig Kit which I will definitely be able to use for other projects). Took just a few hours to put it all together. Going to modify the plans a bit to build a 4′ one out of pressure treated wood for wife to use as a potting bench.
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Jun 20

New Book – VMware vSphere 6.5 Host Resources Deep Dive

Just ordered a copy of Host Resources Deep Dive by @FrankDenneman and @NHagoort. It is on the way!!!

“The VMware vSphere 6.5 Host Resources Deep Dive is a guide to building consistent high-performing ESXi hosts. A book that people canโ€™t put down. Written for administrators, architects, consultants, aspiring VCDX-es and people eager to learn more about the elements that control the behavior of CPU, memory, storage and network resources.”

I have really been looking forward to this one. Can’t wait to dive in ๐Ÿ™‚

Jun 19

Using vSphere HA to Protect vCenter

Had a interesting “discussion” the other day with someone who wasis convinced that it is a best practice is to always deploy vCenter as a separate physical Windows server. One of the reasons for this, in his opinion, was that the vCenter Server could not be protected with vSphere High Availability (HA) since vCenter is required for vSphere HA to function. This is a common misunderstanding of how vSphere HA functions. vCenter is required to configure vSphere HA but once vSphere HA is configured vCenter is NOT required for vSphere HA to protect virtual machines in the cluster.

The ability to provide HA protection of the vCenter Server is one of benefit of deploying vCenter as a virtual machine. Virtualizing vCenter Server also allows you to use the vCenter Server Appliance (VCSA) which saves you a Windows license. vSphere HA can also be used to protect a vCenter Server deployed on a Windows Virtual Machine.

Here is a quick video I did in my lab environment running vSphere 6.5 (I have also tested this on 5.5 and 6.0) which demonstrates how vSphere HA will restart the PSC and vCenter Server in the event of a host failure.

I am running the VCSA in the lab with two VCSAs deployed, one as an external PSC and one a the vCenter Server. For the purpose of the demo I have vSphere DRS set to partially automated to keep VMs from moving around and I have both the VCSA running the PSC and the VCSA running the vCenter Server on the same host. The vSphere HA configuration is the default, except I have disabled admission control due to my resource constraints in the lab. When I power off the host running the VCSAs, they restart on the surviving host in my management cluster.

The little Python script I used in the demo to check if the servers were up or down can be found here:

Post any questions in the comments. Thanks!

Jun 14

It’s been a while…

It has been a good bit since I posted anything new. Just busy with work, family, and other stuff. Some new stuff coming soon. I promise.

Apr 23

Setting up the Weathervane Benchmarking Tool in the Home Lab

If you are looking for something to do in your vSphere home lab this is a neat little project: Weathervane Open Source Benchmarking Tool. Standing up Weathervane in the home lab will provide hands-on for developing skills including creating a template VM, creating a guest customization specification, working with some basic Linux commands, working with an app with multiple tiers, cloning VMs, and monitoring performance metrics.

The architecture of Weathervane can be as simple or complex as you want to make it. The tool provides a way to generate a predictable load to help you gain some experience with deploying a multi-tier application, benchmarking the application, and monitoring performance in a virtualized environment.

Weathervane includes an Auction application made up of different services: workload driver (simulates users accessing the application), web services, database services, application services, etc. All services can be run from a single VM or can be provided across several VMs. This allows for things to be configured more like a “real world” environment and to spread load across multiple guests which can be spread across multiple hosts in a cluster. Here is the logical layout of how I have Weathervane deployed in my home lab:

The Weathervane user guide, located on github, is very detailed and provides step-by-step instructions for deploying, configuring, and running Weathervane. This post provides an overview of how I set up Weathervane in my home lab, an example of the results generated from the Weathervane runs, and a look at the performance metrics I observed in lab during the Weathervane runs.
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Apr 03

Copy SimpliVity Backups to another SimpliVity Cluster

Recently a fellow SA, @agoelammohamed, had a customer who deployed a new production SimpliVity cluster and was planning to decommission and re-purpose the original SimpliVity cluster. Migrating the VMs from the original cluster to the new cluster was easy enough, but they also needed to move around 700 SimpliVity backups, which need to be kept through the configured retention periods, to the new cluster. This can be done from the vSphere Web Client, but @agoelammohamed was looking to see if there was an easy way to automate this process. There is! The SimpliVity REST API includes an operation to copy backups from one OmniStack Cluster to another.

There are a couple other situations where this may come in handy, @agoelammohamed‘s is one and another could be that customer originally deployed SimpliVity for production and later added a DR site and wants to get the existing backups to the DR site.

I put together a powershell script which uses the SimpliVity REST API to automate copying backups from one OmniStack Cluster to another OmniStack Cluster. The script, SVT-CopyBackups.ps1, can be found here:
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Mar 23

Checking VMs for SimpliVity Storage HA

When performing maintenance, upgrades, etc, on a SimpliVity host it is important to verify SimpliVity VMs are in a safe Storage HA state. A safe Storage HA state, or Storage HA equal to Yes, means the virtual machine’s data is fully synchronized and protected in a multi-node SimpliVity cluster.

Verifying the Storage HA state of a VM can be accomplished using a number of different methods:

  1. Using the SimpliVity Management functions in the vSphere Web Client
  2. Using the SimpliVity CLI
  3. Using the SimpliVity REST API

This post provides an overview of verifying Storage HA of SimpliVity virtual machines using the different methods.
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Mar 17

Quick SimpliVity OmniStack Capacity Script

This is a quick script, SVT-Fed-Capactiy.ps1, I put together using Powershell and the SimpliVity REST API to report available, free, and used capacity information for OmniStack Clusters in a SimpliVity Federation, and the OmniStack hosts in each Cluster.

Get the script here:

Just set a couple of simple configuration variables:

  • Line 12-14 – set the OVC mgmt IP ($ovc), username to use ($username), and password ($pass)
  • Line 22 – Here you can set what you want to convert the capacity information to, the REST API returns capacity information in Bytes. Just change the variable to one of the ones above the line. This is set to TiB in the script.
  • Line 23 – Set the number of decimal places to round the capacity conversion to. It is set to 2 in the script.

The script will output the total capacity of each SimpliVity OmniStack Cluster and the physical capacity of each host in the OmniStack Cluster. It looks a little something like this:

Happy Friday! Enjoy.

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